/*
 * Copyright (C) 2011-2014 GUIGUI Simon, fyhertz@gmail.com
 *
 * This file is part of libstreaming (https://github.com/fyhertz/libstreaming)
 *
 * Spydroid is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This source code is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this source code; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package net.majorkernelpanic.screening.rtp;

import net.majorkernelpanic.screening.rtcp.SenderReport;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.util.Random;

/**
 *
 * Each packetizer inherits from this one and therefore uses RTP and UDP.
 *
 */
abstract public class AbstractPacketizer {

  protected static final int rtphl = RtpSocket.RTP_HEADER_LENGTH;

  // Maximum size of RTP packets
  protected final static int MAXPACKETSIZE = RtpSocket.MTU-28;

  protected RtpSocket socket = null;
  protected InputStream is = null;
  protected byte[] buffer;

  protected long ts = 0;

  public AbstractPacketizer() {
    int ssrc = new Random().nextInt();
    ts = new Random().nextInt();
    socket = new RtpSocket();
    socket.setSSRC(ssrc);
  }

  public RtpSocket getRtpSocket() {
    return socket;
  }

  public void setSSRC(int ssrc) {
    socket.setSSRC(ssrc);
  }

  public int getSSRC() {
    return socket.getSSRC();
  }

  public void setInputStream(InputStream is) {
    this.is = is;
  }

  public void setTimeToLive(int ttl) throws IOException {
    socket.setTimeToLive(ttl);
  }

  /**
   * Sets the destination of the stream.
   * @param dest The destination address of the stream
   * @param rtpPort Destination port that will be used for RTP
   * @param rtcpPort Destination port that will be used for RTCP
   */
  public void setDestination(InetAddress dest, int rtpPort, int rtcpPort) {
    socket.setDestination(dest, rtpPort, rtcpPort);
  }

  /** Starts the packetizer. */
  public abstract void start();

  /** Stops the packetizer. */
  public abstract void stop();

  /** Updates data for RTCP SR and sends the packet. */
  protected void send(int length) throws IOException {
    socket.commitBuffer(length);
  }

  /** For debugging purposes. */
  protected static String printBuffer(byte[] buffer, int start,int end) {
    String str = "";
    for (int i=start;i<end;i++) str+=","+Integer.toHexString(buffer[i]&0xFF);
    return str;
  }

  /** Used in packetizers to estimate timestamps in RTP packets. */
  protected static class Statistics {

    public final static String TAG = "Statistics";

    private int count=700, c = 0;
    private float m = 0, q = 0;
    private long elapsed = 0;
    private long start = 0;
    private long duration = 0;
    private long period = 10000000000L;
    private boolean initoffset = false;

    public Statistics() {}

    public Statistics(int count, int period) {
      this.count = count;
      this.period = period;
    }

    public void reset() {
      initoffset = false;
      q = 0; m = 0; c = 0;
      elapsed = 0;
      start = 0;
      duration = 0;
    }

    public void push(long value) {
      elapsed += value;
      if (elapsed>period) {
        elapsed = 0;
        long now = System.nanoTime();
        if (!initoffset || (now - start < 0)) {
          start = now;
          duration = 0;
          initoffset = true;
        }
        // Prevents drifting issues by comparing the real duration of the
        // stream with the sum of all temporal lengths of RTP packets.
        value += (now - start) - duration;
        //Log.d(TAG, "sum1: "+duration/1000000+" sum2: "+(now-start)/1000000+" drift: "+((now-start)-duration)/1000000+" v: "+value/1000000);
      }
      if (c<5) {
        // We ignore the first 20 measured values because they may not be accurate
        c++;
        m = value;
      } else {
        m = (m*q+value)/(q+1);
        if (q<count) q++;
      }
    }

    public long average() {
      long l = (long)m;
      duration += l;
      return l;
    }
  }
}
